Association of Oral Health Values Scale (OHVS) with DMFT Index in Iranian Adults: Zero-Inflated Poisson Regression Analysis

Background: Oral health is a significant global public health priority. The DMFT index is the standard measure for assessing dental caries in communities; however, in Iran, the average DMFT score among adults remains high. The Oral Health Values Scale (OHVS) evaluates behavioral attitudes toward oral health, but its relationship with DMFT has not been studied in the Iranian population. This study presents the first analysis of the association between OHVS and DMFT in Iranian adults Methods: A cross-sectional study was conducted on 499 adults aged 18 to 69 years who visited Shiraz health centers between November 2023 and May 2024. Data were collected using the Oral Health Values Scale (OHVS) questionnaire, which includes four subscales: professional care, appearance/health, dental floss, and preservation of natural teeth. Clinical dental status was assessed using the Decayed, Missing, and Filled Teeth (DMFT) index. Data analysis was performed using Zero-Inflated Poisson (ZIP) regression with the pscl package in R software. Results: The mean DMFT score was 18.06 ± 8.7, with 9.2% of participants being caries-free. The zero-inflated Poisson (ZIP) model (Pseudo R² = 0.727, Vuong test P < 0.001) indicated that natural tooth retention was the strongest predictor of DMFT (incidence rate ratio [IRR] = 1.52, 95% confidence interval [CI]: 1.38–1.68, P < 0.001), followed by appearance/health (IRR = 1.46, P < 0.001), professional care (IRR = 1.40, P = 0.001), and flossing (IRR = 1.20, P = 0.021). Age 30–59 years (IRR = 1.32), poor economic status (IRR = 1.25), male gender (IRR = 1.17), and low education level were also associated with increased DMFT (all P < 0.05). Conversely, university education (IRR = 0.80) and insurance coverage (IRR = 0.87) demonstrated a protective effect. Conclusion: Low OHVS values are associated with increased DMFT rates, indicating reverse causality (referral due to existing caries). OHVS assessment can serve as a screening tool in national prevention programs.